How do children learn generalizations and exceptions?

• Past-tense debate:
  • symbolic rules or connectionist networks?
  • dual-mechanism or single-mechanism?
• Relationship between vocabulary and morphology as evidence
  • Marchman 1992: continuity between vocabulary and morphology
  • Marcus 1992: “overregularization does not correlate with […] children’s vocabularies”

Our approach:

• Empirical landscape of vocabulary ↔️ morphology ↔️ age
• Generalization across (at least a few) languages

1. Is morphology learning driven more by vocabulary or by age?
2. How does morphology learning depend on vocabulary and age?
3. How does morphology learning differ for different verbs?

• “Action Words” → verbs (go)
• “Word Endings” → correct past tense forms of irregular verbs (went)
• “Word Forms” → overregularizations (goed, wented)

• Danish
• English
• Norwegian

• Children who inflect at least one item
• Items that have all three of stem, correct form, overregularized form(s)
• Code each child on each item as:
  • stem only (says go, doesn’t say went/goed/wented)
  • stem + correct (says go and went, doesn’t say goed/wented)
  • stem + overregularized (says go and goed/wented)
• Also each child’s number of verbs producing and age (16–36 months)

For each language:

• says ~ age
• says ~ verbs

For each language and measure:

says ~ how does morphology learning…

verbs + verbs² + depend on vocabulary size?

age + age & verbs + age & verbs² + change with age?

(1 + verbs + age | item) differ for different verbs?

• Irregular morphology learning relates strongly to vocabulary learning
• This relationship is modulated by age: older children…
  • are more likely to produce correct forms and overregularize
  • are less strongly driven to correct inflection by vocabulary size
• and varies across verbs: verbs that are correctly inflected more…
  • are also overregularized more
  • are influenced more by vocabulary size and less by age